A large aircraft fuselage is structurally designed to endure the effects of vehicle maneuvers in the air and on the ground. The altitude of vehicle flight requires that internal fuselage pressure be maintained at levels comfortable to pilots and passengers. A fuselage which is to be pressurized is typically formed to have a generally circular cross-section to maximize strength.
Commercial pressurized aircraft are typically constructed using so-called Semi-monocoque, or semi-structural skin design. This construction includes a series of frames running transverse to a longitudinal axis of the fuselage. The frames are joined with lightweight longitudinal elements called stringers. The stringers are covered with a skin of sheet aluminum.
Cargo floors in such aircraft are typically supported in a flat configuration up from the curved belly of the aircraft with struts and other framing members. These cargo floor framing members may provide little to no structural strength to the fuselage of the aircraft and add weight.